(1) Field of the Invention
The instant invention is directed to a method providing optimum optical trains alignment of optical fiber communication channels in a passive multi-channel fiber optic rotary joint, and more particularly, to such a method that provides proper component positioning in joints between ferrule encased optical fiber terminations and cylindrically bodied miniature collimation lenses that passes signals on multiple, single-mode or multi-mode, optical fiber channels across a continuous rotary interface with low loss, low crosstalk between channels, and low reflection of light back into the input fibers.
(2) Description of the Prior Art
The method, or process, of the present invention has primary utility in connection with the optimization of optical train alignment in optical fiber rotary joints, and especially satisfies a requirement arising in connection with multiple channel optical fiber rotary joints. Multiple channel rotary joints for multi-mode fibers have been developed but exhibit high optical loss and variation of loss with rotation. Additionally, the extreme tolerances associated with single-mode fibers preclude the easy adaptation of rotary joints to handle single-mode fiber. The tight tolerances required by single-mode fibers generally result in excessive loss or excessive variation of loss with rotation. Rotary joints for single-mode fiber have been developed, but are limited to a single on-axis fiber. There are devices which actively align the output fibers to track the input fibers, but these are complicated, require electrical power, and do not allow operation in both directions.
Typically in the heretofore known rotary joints for multi-mode fibers, ferrule encased optical fiber terminations were simply mechanically inserted into associated lens holders for cylindrically bodied miniature collimation lenses and without use of any optical train alignment technique.